1. Field of the Invention
The invention concerns a method, an apparatus and processing plant for the sterilization and/or heat treatment of products in particle form, e.g. bone meal, fish meal and other feedstuffs, possibly also foodstuffs.
2. Description of the Prior Art
It is known to sterilize bone meal and similar organic products in batches by heating the meal while it is stirred in a pressure vessel.
The known pressure vessels for this purpose are large, horizontally-lying vessels with a through-going, horizontal shaft which comprises mechanical stirring elements etc. The shaft is led out through the ends of the vessel via specially constructed stuffing-boxes and bearing arrangements. The heating is effected by the introduction of steam and possibly by heating of the shroud via a steam jacket. Such sterilization plants are characterized by high power consumption, great wear and tear, corrosion if the parts are not made of corrosion-free materials, almost constantly leaking stuffing-boxes, frequent bearing damage due to the leaking stuffing-boxes and due to the fact that it is difficult to seal the hatches necessary for the pressure vessel. The high energy consumption is due, among other things, to the fact that vessels of this kind as a rule cannot be filled more than 20% with meal which is to be sterilized, among other things because the stirring is not good enough if the vessel is filled more.